Bloomberg Photo Service 'Best of the Week': Attendees gather at a Google Inc. Cloud event in San Francisco, California, U.S., on Thursday, March 25, 2014. Google Inc. cut prices on some Internet-based services for businesses by 30 percent or more, stepping up a challenge to Amazon.com Inc. and Microsoft Corp. in cloud computing. Photographer: David Paul Morris/Bloomberg

Google said this week that government requests for data on users had more than doubled over the last four years.

The company released its ninth transparency report, which noted 27,477 worldwide government requests for information from 42,648 users in the second half of 2013. Law enforcement agencies regularly approach the search giant with requests and warrants for data on users' e-mail accounts, YouTube viewing habits and browsing history as they conduct investigations.

Google sometimes fights back on legal grounds or because requests are too broad or unclear; it complied with 64 percent of requests during that period.

However, in the United States that percentage was much higher - answering 83 percent of 10,574 requests.

"You deserve to know when and how governments request user information online, and we'll keep fighting to make sure that's the case," Google legal director Richard Salgado wrote in a blog post.

Yahoo released its second transparency report on Friday, but its numbers showed a decrease in government requests.

In the first half of 2013, Yahoo fielded 12,444 requests from U.S. law enforcement agencies, but only 6,587 requests in the latter half. Over those periods, Yahoo rejected only 2 and 8 percent of request, respectively. Worldwide government requests for Yahoo data showed a similar drop.

The cause of Google's spike and Yahoo's dip remains unclear, in part because of regulations limiting tech companies' transparency in disclosing government surveillance. Both companies are prohibited by law from indicating which, if any, requests came from the National Security Agency - a hot-button issue in the wake of leaks by former NSA contractor Edward Snowden.

The tech companies have the right to disclose NSA requests six months after they are processed, but only in broad terms.

Tech companies like Google, Yahoo, Facebook and Twitter - which all make the vast bulk of their revenue through advertising - are prime targets for law enforcement inquiries due to the ways they collect user data.

"Although FISA was passed by elected representatives and is available for anyone to read, the way the law is used is typically kept secret," Salgado wrote in February.

Google has gone to great lengths to avoid appearing to be a surveillance apparatus. The Mountain View company released its latest law enforcement request data with a playful cartoon video that cast the firm as happy folks doing their jobs and law enforcement as clandestine sunglasses-wearing agents.